Answer:
1) 21 atoms are present: seven of carbon, eight of hydrogen, four of nitrogen and two of oxygen.
2) They all belong to different groups.
Step-by-step explanation:
The following elements are present
carbon
hydrogen
oxygen
nitrogen.
The number of atoms of each element in the molecular formula is represented by the subscript.
The formula given is:C₇H₈N₄O₂
C₇ : It means seven atoms of carbon
H₈: It means eight atoms of hydrogen
N₄: It means four atoms of nitrogen
O₂: It means two atoms of oxygen.
The pattern is that all the elements belong to different groups in the periodic table.
Apart from hydrogen all other three elements are of same period also.